The present invention relates generally to a method and apparatus for feeding a panel from a stack of panels and more particularly to feeding a panel from a stack without damaging the face of the panel.
In the highly automated manufacture of panels and specifically ceiling panels, the panels often are damaged during the manufacturing process. Generally, there is a point in the process when the panels are stacked into a hopper. As panels are removed individually from the bottom of the stack, they may become marred. As the bottom panel is removed from the stack, the facing of this panel is dragged across the backing side of the panels stacked above it. This dragging often leads to the scratching and marring of the facing side of the removed panel.
Various methods have been devised to help alleviate the marring and facial defects occurring to the panels as they are removed from the stack. One such method uses drop feeders that release the bottom panel from the stack and then place the panel on a transport chain just prior to the engaging of the panel by pushers that move the panel along. Unfortunately, the number of panels that can be processed in a given period by this method is rather limited. Other methods include hand feeding the individual panels for processing, but the number of panels that can be processed by this method is also quite limited.
A further method used to limit facial defects in panels as they are being processed is to operate in a xe2x80x9cone-in/one-outxe2x80x9d mode. This method essentially eliminates the need to stack the panels in a hopper. Unfortunately, this method requires the use of expensive servo drives, chain speed sensors, panel position sensors, transport chain pusher sensors and complex logic to keep track of the position of each panel relative to the pusher.
Thus, a method for delivering panels with fewer facial defects is needed. A method and apparatus is needed that can economically deliver panels one at a time from a hopper, at acceptable production rates, without the panels experiencing a significant incidence of facial defects during this process step.
The present invention comprises both a method and apparatus for reducing the incidence of facial defects to the face of a panel as it is removed from a stack of panels. The apparatus provides a pair of synchronized cams working together to engage a stack of panels as the bottom most panel is being removed from the stack. By engaging the stack of panels with the cams, the bottom most panel can be removed with less likelihood of marring its facing.
In greater detail, the invention comprises an apparatus for feeding a first panel from a stack of panels residing above the first panel. The apparatus includes a pusher for engaging and feeding the first panel from the stack. Additionally, a first cam having a first major lobe and a first minor lobe is provided. The profile of the first cam is such that the angle of the arc of the major lobe is greater than the angle of the arc of the minor lobe. The first major lobe engages the trailing edge portion of the stack residing above the first panel and lifts the stack residing above the first panel as the pusher moves the trailing edge of the first panel out from under the stack at a first position. A second cam also having a major lobe and a minor lobe is provided to help support the stack of panels. The difference between the first cam and the second cam is that the profile of the second cam is such that the angle of the arc of the major lobe is less than the angle of the arc of the minor lobe. The stack of panels is supported and lifted as the major lobe of the second cam engages the leading edge portion of the stack of panels as the first panel is pushed out from under the stack at a second position.
Furthermore, after the first panel is moved out from under the stack, the stack of panels is lowered and the process begins again when the minor lobes of the cams or the transition zones engaging the stack of panels. The cams are mechanically linked to the tenoner transport chains to provide proper timing of the lifting and lowering of the stack relative to the position of the pusher. Also, the major lobe of the first cam has a greater angular profile than the major lobe of the second cam so as to provide a longer support or lifting cycle. The first and second cam shafts are mechanically linked to synchronize the action.
Additionally, a method for delivering a panel is provided including the steps of pushing a first panel from a stack of panels residing above the first panel. The stack of panels has both a trailing edge and a leading edge. Then the trailing edge of the stack residing above the first panel is supported as the first panel trailing edge is pushed out from under the trailing edge portion of the stack at a first position. Next, as the panel is pushed along, the leading edge portion of the stack is further supported as the trailing edge of the first panel is pushed out from under the leading edge portion of the stack at a second position. The panel is then removed from the stack and the process can begin again.